I will be very transparent with them though because I do not want them to get discouraged after another rejected offer. 

So, we rejected that offer and stated that we would ONLY accept that offer if we were to receive a $10k credit at closing.

My electrician said that it wound't be a huge deal converting back to a SFH and that he would even take some of the price down if he could reuse the old meter, amp, boxes.I am offering around $100K for the house (they just countered to 110), my original was $85k and that offer was rejected.  

Or at least maybe they will counter to a number that you are comfortable with.The worst that can happen is that they will outright reject your offer, in which case you can make them a new offer.

The notary accepted them as valid but the title company said the underwriters are rejecting them. 

The sellers were initially going to reject that and fight the builder legally instead.

If the brother’s credit check (or one of the other applicants) reveals an eviction or another red flag then I would decline all of the applicants because if u just deny one person they will likely sneak in the rejected potential tenant.

No, sorry, you should find your own deals ... it is an unrealistic and unwise expectation IMO that you should be able to casually waltz into any market and pick something up right off the MLS that is going to consistently net you great returns throughout the lifetime of ownership ... such "deals" like that are ones that all of the local investors have already long since picked over and rejected, and if a property seems as such it is probably because you are not familiar with investing and/or the market and you are missing something as in the example above.

It does take a lot of work looking at the houses and most of the offers are going to get rejected.

Then it would be the owners decision to reject the offer.